Norway is the most expensive country I've been so far, I'm not kidding. If you don't want to spend way too much money during your trip you should read some tips from me. Of course I don't want to sound "cheap", but saving money is important, especially when you travel a lot.
Really convenient option for tourists is Oslo pass, a card which gives you free entry to more than 30 museums, free travel by public transportation, parking and other attractions as well as a lot of discounts. You can buy it in tourism office. For example Oslo pass for 24 hours costs 330 NOK for adults. You can find more information about it here.
You should take advantages of free attractions in Oslo such as Vigeland Sculpture Park, Akershus Fortress or Opera House. You don't need to pay for them, so you can save more money in your wallet.
Some museums in Oslo have free entry on Sunday, so you should look for the information on their websites before you see one. For example when I was in Oslo, I didn't have to pay for Munch Museum.
The other useful, but kind of obvious, tip is the fact that you should look for a hotel/hostel with breakfast included or with a kitchen where you can prepare food. Eating breakfast outside seems to be fancy and probably it would be a good start of a day, but you don't want to spend all your money on something which you could eat in hotel or made it in "your own" kitchen for less price. Of course you shouldn't resign from eating outside, but do it wisely (I recommened some places where you can eat here). Remember that food in restaurant is about 30 dollars per person and coffee in the cafe is about 5 dollars.
The centre of Oslo is pretty small, so in general it's really easy to walk everywhere. All the main attractions are close to each other even if it doesn't look like that on the map. The longest walk I had, to the Vigeland Sculpture Park, lasted about 30 minutes, more or less. Of course only expectations are islands where you can't walk physically and you need to use a water tram.
The last thing I want to mention about is alcohol. Norway has really strong antialcohol politics, that's why all kinds of alcohols are pricey and for example people can buy them in supermarket only in some days, in identified hours. For instance beer costs about 10 dollars in Norway.
Don't be afraid - even if Norway is pretty pricey, this country is still one of the most beutiful place I've ever seen and of course I've seen only a little part. Go there if you have an opportunity!
Do you have any other tips how to save money in expensive places?